Refactor: moved the hash function from assoc.c to hash.c

1 files changed, 0 insertions, 419 deletions

diff --git a/assoc.c b/assoc.c
index 59711d4..cbbfdeb 100644
--- a/assoc.c
+++ b/assoc.c
@@ -30,425 +30,6 @@
 static pthread_cond_t maintenance_cond = PTHREAD_COND_INITIALIZER;
 
 
-/*
- * Since the hash function does bit manipulation, it needs to know
- * whether it's big or little-endian. ENDIAN_LITTLE and ENDIAN_BIG
- * are set in the configure script.
- */
-#if ENDIAN_BIG == 1
-# define HASH_LITTLE_ENDIAN 0
-# define HASH_BIG_ENDIAN 1
-#else
-# if ENDIAN_LITTLE == 1
-#  define HASH_LITTLE_ENDIAN 1
-#  define HASH_BIG_ENDIAN 0
-# else
-#  define HASH_LITTLE_ENDIAN 0
-#  define HASH_BIG_ENDIAN 0
-# endif
-#endif
-
-#define rot(x,k) (((x)<<(k)) ^ ((x)>>(32-(k))))
-
-/*
--------------------------------------------------------------------------------
-mix -- mix 3 32-bit values reversibly.
-
-This is reversible, so any information in (a,b,c) before mix() is
-still in (a,b,c) after mix().
-
-If four pairs of (a,b,c) inputs are run through mix(), or through
-mix() in reverse, there are at least 32 bits of the output that
-are sometimes the same for one pair and different for another pair.
-This was tested for:
-* pairs that differed by one bit, by two bits, in any combination
-  of top bits of (a,b,c), or in any combination of bottom bits of
-  (a,b,c).
-* "differ" is defined as +, -, ^, or ~^.  For + and -, I transformed
-  the output delta to a Gray code (a^(a>>1)) so a string of 1's (as
-  is commonly produced by subtraction) look like a single 1-bit
-  difference.
-* the base values were pseudorandom, all zero but one bit set, or
-  all zero plus a counter that starts at zero.
-
-Some k values for my "a-=c; a^=rot(c,k); c+=b;" arrangement that
-satisfy this are
-    4  6  8 16 19  4
-    9 15  3 18 27 15
-   14  9  3  7 17  3
-Well, "9 15 3 18 27 15" didn't quite get 32 bits diffing
-for "differ" defined as + with a one-bit base and a two-bit delta.  I
-used http://burtleburtle.net/bob/hash/avalanche.html to choose
-the operations, constants, and arrangements of the variables.
-
-This does not achieve avalanche.  There are input bits of (a,b,c)
-that fail to affect some output bits of (a,b,c), especially of a.  The
-most thoroughly mixed value is c, but it doesn't really even achieve
-avalanche in c.
-
-This allows some parallelism.  Read-after-writes are good at doubling
-the number of bits affected, so the goal of mixing pulls in the opposite
-direction as the goal of parallelism.  I did what I could.  Rotates
-seem to cost as much as shifts on every machine I could lay my hands
-on, and rotates are much kinder to the top and bottom bits, so I used
-rotates.
--------------------------------------------------------------------------------
-*/
-#define mix(a,b,c) \
-{ \
-  a -= c;  a ^= rot(c, 4);  c += b; \
-  b -= a;  b ^= rot(a, 6);  a += c; \
-  c -= b;  c ^= rot(b, 8);  b += a; \
-  a -= c;  a ^= rot(c,16);  c += b; \
-  b -= a;  b ^= rot(a,19);  a += c; \
-  c -= b;  c ^= rot(b, 4);  b += a; \
-}
-
-/*
--------------------------------------------------------------------------------
-final -- final mixing of 3 32-bit values (a,b,c) into c
-
-Pairs of (a,b,c) values differing in only a few bits will usually
-produce values of c that look totally different.  This was tested for
-* pairs that differed by one bit, by two bits, in any combination
-  of top bits of (a,b,c), or in any combination of bottom bits of
-  (a,b,c).
-* "differ" is defined as +, -, ^, or ~^.  For + and -, I transformed
-  the output delta to a Gray code (a^(a>>1)) so a string of 1's (as
-  is commonly produced by subtraction) look like a single 1-bit
-  difference.
-* the base values were pseudorandom, all zero but one bit set, or
-  all zero plus a counter that starts at zero.
-
-These constants passed:
- 14 11 25 16 4 14 24
- 12 14 25 16 4 14 24
-and these came close:
-  4  8 15 26 3 22 24
- 10  8 15 26 3 22 24
- 11  8 15 26 3 22 24
--------------------------------------------------------------------------------
-*/
-#define final(a,b,c) \
-{ \
-  c ^= b; c -= rot(b,14); \
-  a ^= c; a -= rot(c,11); \
-  b ^= a; b -= rot(a,25); \
-  c ^= b; c -= rot(b,16); \
-  a ^= c; a -= rot(c,4);  \
-  b ^= a; b -= rot(a,14); \
-  c ^= b; c -= rot(b,24); \
-}
-
-#if HASH_LITTLE_ENDIAN == 1
-uint32_t hash(
-  const void *key,       /* the key to hash */
-  size_t      length,    /* length of the key */
-  const uint32_t    initval)   /* initval */
-{
-  uint32_t a,b,c;                                          /* internal state */
-  union { const void *ptr; size_t i; } u;     /* needed for Mac Powerbook G4 */
-
-  /* Set up the internal state */
-  a = b = c = 0xdeadbeef + ((uint32_t)length) + initval;
-
-  u.ptr = key;
-  if (HASH_LITTLE_ENDIAN && ((u.i & 0x3) == 0)) {
-    const uint32_t *k = key;                           /* read 32-bit chunks */
-#ifdef VALGRIND
-    const uint8_t  *k8;
-#endif /* ifdef VALGRIND */
-
-    /*------ all but last block: aligned reads and affect 32 bits of (a,b,c) */
-    while (length > 12)
-    {
-      a += k[0];
-      b += k[1];
-      c += k[2];
-      mix(a,b,c);
-      length -= 12;
-      k += 3;
-    }
-
-    /*----------------------------- handle the last (probably partial) block */
-    /*
-     * "k[2]&0xffffff" actually reads beyond the end of the string, but
-     * then masks off the part it's not allowed to read.  Because the
-     * string is aligned, the masked-off tail is in the same word as the
-     * rest of the string.  Every machine with memory protection I've seen
-     * does it on word boundaries, so is OK with this.  But VALGRIND will
-     * still catch it and complain.  The masking trick does make the hash
-     * noticably faster for short strings (like English words).
-     */
-#ifndef VALGRIND
-
-    switch(length)
-    {
-    case 12: c+=k[2]; b+=k[1]; a+=k[0]; break;
-    case 11: c+=k[2]&0xffffff; b+=k[1]; a+=k[0]; break;
-    case 10: c+=k[2]&0xffff; b+=k[1]; a+=k[0]; break;
-    case 9 : c+=k[2]&0xff; b+=k[1]; a+=k[0]; break;
-    case 8 : b+=k[1]; a+=k[0]; break;
-    case 7 : b+=k[1]&0xffffff; a+=k[0]; break;
-    case 6 : b+=k[1]&0xffff; a+=k[0]; break;
-    case 5 : b+=k[1]&0xff; a+=k[0]; break;
-    case 4 : a+=k[0]; break;
-    case 3 : a+=k[0]&0xffffff; break;
-    case 2 : a+=k[0]&0xffff; break;
-    case 1 : a+=k[0]&0xff; break;
-    case 0 : return c;  /* zero length strings require no mixing */
-    }
-
-#else /* make valgrind happy */
-
-    k8 = (const uint8_t *)k;
-    switch(length)
-    {
-    case 12: c+=k[2]; b+=k[1]; a+=k[0]; break;
-    case 11: c+=((uint32_t)k8[10])<<16;  /* fall through */
-    case 10: c+=((uint32_t)k8[9])<<8;    /* fall through */
-    case 9 : c+=k8[8];                   /* fall through */
-    case 8 : b+=k[1]; a+=k[0]; break;
-    case 7 : b+=((uint32_t)k8[6])<<16;   /* fall through */
-    case 6 : b+=((uint32_t)k8[5])<<8;    /* fall through */
-    case 5 : b+=k8[4];                   /* fall through */
-    case 4 : a+=k[0]; break;
-    case 3 : a+=((uint32_t)k8[2])<<16;   /* fall through */
-    case 2 : a+=((uint32_t)k8[1])<<8;    /* fall through */
-    case 1 : a+=k8[0]; break;
-    case 0 : return c;  /* zero length strings require no mixing */
-    }
-
-#endif /* !valgrind */
-
-  } else if (HASH_LITTLE_ENDIAN && ((u.i & 0x1) == 0)) {
-    const uint16_t *k = key;                           /* read 16-bit chunks */
-    const uint8_t  *k8;
-
-    /*--------------- all but last block: aligned reads and different mixing */
-    while (length > 12)
-    {
-      a += k[0] + (((uint32_t)k[1])<<16);
-      b += k[2] + (((uint32_t)k[3])<<16);
-      c += k[4] + (((uint32_t)k[5])<<16);
-      mix(a,b,c);
-      length -= 12;
-      k += 6;
-    }
-
-    /*----------------------------- handle the last (probably partial) block */
-    k8 = (const uint8_t *)k;
-    switch(length)
-    {
-    case 12: c+=k[4]+(((uint32_t)k[5])<<16);
-             b+=k[2]+(((uint32_t)k[3])<<16);
-             a+=k[0]+(((uint32_t)k[1])<<16);
-             break;
-    case 11: c+=((uint32_t)k8[10])<<16;     /* @fallthrough */
-    case 10: c+=k[4];                       /* @fallthrough@ */
-             b+=k[2]+(((uint32_t)k[3])<<16);
-             a+=k[0]+(((uint32_t)k[1])<<16);
-             break;
-    case 9 : c+=k8[8];                      /* @fallthrough */
-    case 8 : b+=k[2]+(((uint32_t)k[3])<<16);
-             a+=k[0]+(((uint32_t)k[1])<<16);
-             break;
-    case 7 : b+=((uint32_t)k8[6])<<16;      /* @fallthrough */
-    case 6 : b+=k[2];
-             a+=k[0]+(((uint32_t)k[1])<<16);
-             break;
-    case 5 : b+=k8[4];                      /* @fallthrough */
-    case 4 : a+=k[0]+(((uint32_t)k[1])<<16);
-             break;
-    case 3 : a+=((uint32_t)k8[2])<<16;      /* @fallthrough */
-    case 2 : a+=k[0];
-             break;
-    case 1 : a+=k8[0];
-             break;
-    case 0 : return c;  /* zero length strings require no mixing */
-    }
-
-  } else {                        /* need to read the key one byte at a time */
-    const uint8_t *k = key;
-
-    /*--------------- all but the last block: affect some 32 bits of (a,b,c) */
-    while (length > 12)
-    {
-      a += k[0];
-      a += ((uint32_t)k[1])<<8;
-      a += ((uint32_t)k[2])<<16;
-      a += ((uint32_t)k[3])<<24;
-      b += k[4];
-      b += ((uint32_t)k[5])<<8;
-      b += ((uint32_t)k[6])<<16;
-      b += ((uint32_t)k[7])<<24;
-      c += k[8];
-      c += ((uint32_t)k[9])<<8;
-      c += ((uint32_t)k[10])<<16;
-      c += ((uint32_t)k[11])<<24;
-      mix(a,b,c);
-      length -= 12;
-      k += 12;
-    }
-
-    /*-------------------------------- last block: affect all 32 bits of (c) */
-    switch(length)                   /* all the case statements fall through */
-    {
-    case 12: c+=((uint32_t)k[11])<<24;
-    case 11: c+=((uint32_t)k[10])<<16;
-    case 10: c+=((uint32_t)k[9])<<8;
-    case 9 : c+=k[8];
-    case 8 : b+=((uint32_t)k[7])<<24;
-    case 7 : b+=((uint32_t)k[6])<<16;
-    case 6 : b+=((uint32_t)k[5])<<8;
-    case 5 : b+=k[4];
-    case 4 : a+=((uint32_t)k[3])<<24;
-    case 3 : a+=((uint32_t)k[2])<<16;
-    case 2 : a+=((uint32_t)k[1])<<8;
-    case 1 : a+=k[0];
-             break;
-    case 0 : return c;  /* zero length strings require no mixing */
-    }
-  }
-
-  final(a,b,c);
-  return c;             /* zero length strings require no mixing */
-}
-
-#elif HASH_BIG_ENDIAN == 1
-/*
- * hashbig():
- * This is the same as hashword() on big-endian machines.  It is different
- * from hashlittle() on all machines.  hashbig() takes advantage of
- * big-endian byte ordering.
- */
-uint32_t hash( const void *key, size_t length, const uint32_t initval)
-{
-  uint32_t a,b,c;
-  union { const void *ptr; size_t i; } u; /* to cast key to (size_t) happily */
-
-  /* Set up the internal state */
-  a = b = c = 0xdeadbeef + ((uint32_t)length) + initval;
-
-  u.ptr = key;
-  if (HASH_BIG_ENDIAN && ((u.i & 0x3) == 0)) {
-    const uint32_t *k = key;                           /* read 32-bit chunks */
-#ifdef VALGRIND
-    const uint8_t  *k8;
-#endif /* ifdef VALGRIND */
-
-    /*------ all but last block: aligned reads and affect 32 bits of (a,b,c) */
-    while (length > 12)
-    {
-      a += k[0];
-      b += k[1];
-      c += k[2];
-      mix(a,b,c);
-      length -= 12;
-      k += 3;
-    }
-
-    /*----------------------------- handle the last (probably partial) block */
-    /*
-     * "k[2]<<8" actually reads beyond the end of the string, but
-     * then shifts out the part it's not allowed to read.  Because the
-     * string is aligned, the illegal read is in the same word as the
-     * rest of the string.  Every machine with memory protection I've seen
-     * does it on word boundaries, so is OK with this.  But VALGRIND will
-     * still catch it and complain.  The masking trick does make the hash
-     * noticably faster for short strings (like English words).
-     */
-#ifndef VALGRIND
-
-    switch(length)
-    {
-    case 12: c+=k[2]; b+=k[1]; a+=k[0]; break;
-    case 11: c+=k[2]&0xffffff00; b+=k[1]; a+=k[0]; break;
-    case 10: c+=k[2]&0xffff0000; b+=k[1]; a+=k[0]; break;
-    case 9 : c+=k[2]&0xff000000; b+=k[1]; a+=k[0]; break;
-    case 8 : b+=k[1]; a+=k[0]; break;
-    case 7 : b+=k[1]&0xffffff00; a+=k[0]; break;
-    case 6 : b+=k[1]&0xffff0000; a+=k[0]; break;
-    case 5 : b+=k[1]&0xff000000; a+=k[0]; break;
-    case 4 : a+=k[0]; break;
-    case 3 : a+=k[0]&0xffffff00; break;
-    case 2 : a+=k[0]&0xffff0000; break;
-    case 1 : a+=k[0]&0xff000000; break;
-    case 0 : return c;              /* zero length strings require no mixing */
-    }
-
-#else  /* make valgrind happy */
-
-    k8 = (const uint8_t *)k;
-    switch(length)                   /* all the case statements fall through */
-    {
-    case 12: c+=k[2]; b+=k[1]; a+=k[0]; break;
-    case 11: c+=((uint32_t)k8[10])<<8;  /* fall through */
-    case 10: c+=((uint32_t)k8[9])<<16;  /* fall through */
-    case 9 : c+=((uint32_t)k8[8])<<24;  /* fall through */
-    case 8 : b+=k[1]; a+=k[0]; break;
-    case 7 : b+=((uint32_t)k8[6])<<8;   /* fall through */
-    case 6 : b+=((uint32_t)k8[5])<<16;  /* fall through */
-    case 5 : b+=((uint32_t)k8[4])<<24;  /* fall through */
-    case 4 : a+=k[0]; break;
-    case 3 : a+=((uint32_t)k8[2])<<8;   /* fall through */
-    case 2 : a+=((uint32_t)k8[1])<<16;  /* fall through */
-    case 1 : a+=((uint32_t)k8[0])<<24; break;
-    case 0 : return c;
-    }
-
-#endif /* !VALGRIND */
-
-  } else {                        /* need to read the key one byte at a time */
-    const uint8_t *k = key;
-
-    /*--------------- all but the last block: affect some 32 bits of (a,b,c) */
-    while (length > 12)
-    {
-      a += ((uint32_t)k[0])<<24;
-      a += ((uint32_t)k[1])<<16;
-      a += ((uint32_t)k[2])<<8;
-      a += ((uint32_t)k[3]);
-      b += ((uint32_t)k[4])<<24;
-      b += ((uint32_t)k[5])<<16;
-      b += ((uint32_t)k[6])<<8;
-      b += ((uint32_t)k[7]);
-      c += ((uint32_t)k[8])<<24;
-      c += ((uint32_t)k[9])<<16;
-      c += ((uint32_t)k[10])<<8;
-      c += ((uint32_t)k[11]);
-      mix(a,b,c);
-      length -= 12;
-      k += 12;
-    }
-
-    /*-------------------------------- last block: affect all 32 bits of (c) */
-    switch(length)                   /* all the case statements fall through */
-    {
-    case 12: c+=k[11];
-    case 11: c+=((uint32_t)k[10])<<8;
-    case 10: c+=((uint32_t)k[9])<<16;
-    case 9 : c+=((uint32_t)k[8])<<24;
-    case 8 : b+=k[7];
-    case 7 : b+=((uint32_t)k[6])<<8;
-    case 6 : b+=((uint32_t)k[5])<<16;
-    case 5 : b+=((uint32_t)k[4])<<24;
-    case 4 : a+=k[3];
-    case 3 : a+=((uint32_t)k[2])<<8;
-    case 2 : a+=((uint32_t)k[1])<<16;
-    case 1 : a+=((uint32_t)k[0])<<24;
-             break;
-    case 0 : return c;
-    }
-  }
-
-  final(a,b,c);
-  return c;
-}
-#else /* HASH_XXX_ENDIAN == 1 */
-#error Must define HASH_BIG_ENDIAN or HASH_LITTLE_ENDIAN
-#endif /* HASH_XXX_ENDIAN == 1 */
-
 typedef  unsigned long  int  ub4;   /* unsigned 4-byte quantities */
 typedef  unsigned       char ub1;   /* unsigned 1-byte quantities */